Anthomyza caesarea, Roháček, 2020

Roháček, Jindřich, 2020, Anthomyzidae (Diptera) of Taiwan: new species but no new records, Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 269-290 : 278-284

Anthomyza caesarea sp. nov.

( Figs 22–25 , 28 ¯47)

Type material. HƟĿƟŦYPൾ:, labelled: “ Taiwan Taichung, Pi Lu Shan [= Bilushan], 24-25/VII/1990,W.C.Chuang, Sweeping net” and “ Holotypus, Anthomyza caesarea sp. n., J. Roháček det. 2019” (red label). The specimen is dry mounted on a minuten pin but somewhat damaged ( Fig. 22 ), with left wing and some legs or its parts absent, abdomen cleared, with genitalia dissected and all parts preserved in glycerine in a pinned plastic tube together with left hind leg ( NMNS). PARAŦYPൾඌ: 2 ♀♀, with same label data as for the holotype, only second (type) label yellow with “ Paratypus ♀ ”; both specimens somewhat damaged ( Figs 23, 25 ), one (on minuten pin) without left wing and with right wing removed for photography and preserved in glycerine together with abdomen, the other (glued on a pinned triangular card) with wings stuck together basally, each specimen with abdomen detached, cleared and preserved in glycerine in a plastic tube pinned below ( NMNS).

Description. Male. Large species, total body length 3.26 mm; distinctly bicoloured, dorsally blackish brown, ventrally yellow ( Fig. 22 ), very sparsely greyish microtomentose and hence rather shining, particularly dorsally.

Head slightly longer than high, with somewhat projecting frons and receding face, thus angular in profile (cf. Figs 22, 25 ). Occiput distinctly concave dorsomedially (cf. Fig. 23 ), dark brown dorsolaterally but with medial band above foramen pale brown to ochreous and completely ochreous to yellow below foramen. Frons largely dull yellow to (posteriorly) ochreous, only frontal (including darker ocellar) triangle and posterior part of orbit brown and shining despite some grey microtomentum. Orbits dull yellow and whitish microtomentose anteriorly (up to posterior ors), brown and more shiny posteriorly. Frontal triangle well delimited, narrow, reaching anterior third of frons. Frontal lunule small, depressed, yellow. Face narrow, medially concave and yellow, laterally pale brown; parafacialia and gena ochreous but silvery-white microtomentose, both bordered by relatively wide, pale-brown marginal stripe; postgena yellow like ventral part of occiput, somewhat whitish microtomentose and with posteroventral corner rounded rectangular; mouthparts ochreous. Cephalic chaetotaxy (cf. Figs 22, 25 ): pvt relatively long but thin, strongly crossed; vti and oc unusually long, by far the longest of cephalic setae but oc thinner than vti; vte about as long as posterior ors; 3 ors of moderate length, middle ors subequal to or slightly shorter than posterior ors, anterior ors distinctly shorter than others; no microsetula in front of anterior ors; medial microsetulae in anterior third of frons unusually long and numerous, in 6 irregular pairs; 1 or 2 setulae behind vte slightly longer than uppermost postocular; 7–8 relatively long postocular setulae, in single row; postgena with a few scattered setulae, also 2 or 3 relatively short posteroventral setae; 1 weak vi, shorter and finer than middle ors; subvibrissa about two-thirds length of vi and finer; 4 fine and sparse, relatively long peristomal setulae but slightly shorter than subvibrissa. Palpus small and slender, ochreous yellow, with 1 dark preapical seta and 3 or 4 paler ventral setulae. Eye ovoid ( Fig. 22 ), with longest diameter oblique and about 1.5 times as long as the shortest. Shortest genal height about 0.1 times as long as shortest eye diameter. Antenna geniculate, entirely yellow; pedicel with relatively long exclinate dorsal seta; 1st flagellomere with white pilosity on anteroventral margin slightly longer than that of arista. Arista brown to pale brown (basal segment lighter brown) and 1.9 times as long as antenna, very shortly ciliate.

Thorax as wide as head, dorsally brown to blackish, sparsely grey microtomentose and relatively shining, only narrow notopleural area yellow. Pleural part of thorax largely yellow but dorsally with broad longitudinal brown band extended from cervix to metanotum (cf. Figs 22, 25 ). Thoracic chaetotaxy (all macrosetae relatively thin): 1 hu (as long as anterior npl); 2 npl (anterior longer); 1 short weak prs; 1 subequally short sa; 1 long pa; 2 long postsutural dc (anterior shorter than posterior) and 5 or 6 dc microsetae in front of them; 4 rather irregular rows of ac microsetae on suture, only 2 medial rows more posteriorly, almost reaching to level of posterior dc; 2 sc, laterobasal small and weak (shorter than prs), apical as long as posterior dc; 1 minute hair-like and pale ppl; 2 relatively strong and dark stpl, anterior only slightly shorter, and 1 pale setula in dorsal half of sternopleuron, its ventral part with a cluster of 5 or 6 longer yellow setae. Scutellum rounded triangular, distinctly convex dorsally. Subscutellum well developed and more densely grey microtomentose. Legs entirely pale yellow, including last tarsal segments. f1 (cf. Fig. 29 ) with short ctenidial spine, distinctly shorter than maximum width of t1; f2 ( Fig. 30 ) with a row of fine but erect posteroventral setae in proximal half; f3 with long anteroventral row of setae, 7 of which (in distal third) thickened and shortened ( Fig. 31 ); t2 with very short ventroapical seta ( Fig. 30 ); t1, t3 and all tarsi simply setulose, only hind basitarsus with several ventrobasal setulae longer ( Fig. 31 ). Wing (cf. Fig. 24 ) very long, narrow, with pale ochreous or brown veins. Wing membrane with unusual broad, brown longitudinal band running in middle of wing across its whole length. C with distinct but sparse spinulae between apices of R1 and R2+3. R2+3 very long, running parallel and close to C with apex upcurving; R4+5 very slightly bent, subparallel to M distally. Cell dm narrow, elongate, widened distally, with r-m situated in its proximal two-fifths. Apical portion of CuA1 distinctly longer than dm-cu and reaching wing margin; A1 short, ending far from margin. Alula small, narrow. Wing measurements (holotype): length 3.22 mm, width 0.93 mm, Cs3: Cs4 = 1.27, rm\dm-cu: dm-cu = 3.04. Haltere yellow, with stem more or less darkened.

Abdomen elongate, slender. Preabdominal terga brown to blackish brown, with some greyish microtomentum, subshining to shining (laterally), distinctly setose. T1 only laterally fused with T2, somewhat narrower and shorter than T2; T2–T5 large, subequal in length, broad and reaching far onto ventral side of abdomen. Preabdominal sterna narrow, yellow to pale yellow, with sparse whitish microtomentum; S1 not observed (lost during preparation). S2–S5 more finely setose than adjacent terga. S2 about as long as wide, wider than S3; S3 and S4 somewhat longer than wide; S5 largest, wider than long, widened posteriorly and more densely setose than other sterna. Postabdomen ( Fig. 28 ): T6 transverse, entirely membranous and unpigmented, bare. S6–S8 fused together but with fusion lines distinct; S6 and S7 strongly asymmetrical, situated on left side of postabdomen, both strikingly paler (ochreous) than S8 and with only anterior marginal stripe dark brown; S6 with 2 setae, S7 with 1 seta; S8 longer than S6+S7 and dark brown, larger on left side and setose in posterior half.

Genitalia. Epandrium ( Figs 28, 32 ) subspherical, slightly broader than high, relatively long, with relatively dense setosity including 2 pairs of longer setae; anal fissure very small and narrow, rounded subtriangular. Cercus very small and short, finely micropubescent, with fine and pale setae, apical seta longest. Medandrium high but narrow, slightly tapered dorsally, dorsolateral corners hardly projecting. Gonostylus ( Figs 28, 32 , 36 ) relatively long (about 0.75 times epandrial height) but slender and only proximally broad, strongly tapered distally to acute apex, slightly incurved in caudal view ( Fig. 32 ), ochreous yellow in contrast to dark-brown epandrium, almost lacking micropubescence, with only a few setulae on outer side but densely setose on inner side. Hypandrium ( Figs 33, 35 ) rather robust and compact, anterior internal lobes low, not projecting dorsally. Transandrium ( Fig. 34 ) rather simple, dorsally with dark transverse ledge, medially with distinct caudal process being narrowed and pale-pigmented ventrally where coalesced with basal membrane. Pregonite ( Figs 33, 35 ) completely fused to hypandrium, its anterior part slightly protruding ventrally and bent medially (as in A. flavosterna ), anteromedially with 3 or 4 setae, posteriorly with a group of 3 or 4 closely clustered setae. Postgonite ( Figs 33, 35 ) slender, longer than in A. flavosterna , apically blunt and with several sensilla but without any seta (also absent in A. flavosterna ). Basal membrane bulging ( Fig. 35 ), larger than in A. flavosterna , densely overgrown by numerous short and dense hyaline spines ( Fig. 34 ). Aedeagal part of folding apparatus without spines or tubercles, only finely striated ( Fig. 38 ). Connecting sclerite relatively large and long but partly unpigmented and weakly sclerotized ( Fig. 38 ). Phallapodeme with very slender basal half and with basal end relatively symmetrically forked ( Fig. 37 ), apically very shortly bicuspidate ( Fig. 38 ). Aedeagus with phallophore simple but elongate ( Fig. 38 ), of similar construction to that of A. flavosterna . Distiphallus large, bifid from near its base. Saccus relatively short, vesiculate, largely membranous, covered by dense, short and broad but hyaline spines ( Fig. 38 ). Filum very robust and broad along most of its length ( Fig. 38 ), with only base narrower, preapically curved and projecting as single elongate, sinuate process that is apically curved, hook-like (see Fig. 39 ); most of its surface covered by small tubercles ( Fig. 38 ). Ejacapodeme very small, with short projection ( Fig. 38 ).

Female. Similar to male unless mentioned otherwise. Total body length 3.40–3.46 mm. Frontal triangle ( Fig. 23 ) pale ochreous, often lighter than adjacent parts of frons but ocellar triangle dark brown (as in male). Face, parafacialia, gena and postgena yellow and marginal stripe of parafacialia and gena paler. Antenna darker, orange ( Fig. 25 ). Eye less elongate, its longest diameter 1.38–1.44 times as long as shortest. Ctenidial spine on f1 ( Fig. 29 ) small as in male. Both f2 and f3 posteroventrally simply setulose. Wing with r-m situated at midlength of dm cell ( Fig. 24 ). Wing measurements: length 3.49–3.98 mm, width 0.99–1.05 mm, Cs3: Cs4 = 1.17–1.38, rm\dm-cu: dm-cu = 2.87–3.38. Abdomen with T2–T5 subequal in length but shorter and distinctly more transverse than in male, all dark brown but lighter ( Fig. 25 ) than postabdominal T6 and T7. Preabdominal sterna pale yellow and becoming slightly wider posteriorly. S2 shortest, S2 and S3 narrower than long, S4 and S5 about as long as broad, S5 largest and (posteriorly) widest.

Postabdomen ( Figs 40–42 ) relatively long, gradually tapered posteriorly, with the narrow, weakly sclerotized and pale-pigmented end (from 8th segment) withdrawn at rest into large 7th segment (see Fig. 25 ). T6 broad ( Fig. 41 ), almost as wide as T5 but only about half its length, somewhat lighter than T7+S7, densely setose. S6 very small ( Fig. 42 ), narrower than S5, pale yellow, with relatively long but thin setae in posterior half. Tergosternum T7+S7 ( Figs 40–42 ) prolonged, tapered posteriorly and characteristically formed, with tergal part enlarged and setose, and sternal part extremely reduced (narrowed); largely blackish brown but dorsally with large, irregular posteromedial pale-brown area ( Fig. 41 ); extended laterally far onto ventral side ( Fig. 42 ) leaving only a very narrow, medial membranous sternal strip (= remnant of S7) bearing single pair of setae. T8 elongate and narrow (narrower than in A. flavosterna ), pale-pigmented, with fine transverse microsculpture ( Fig. 41 ) and fine posterior and posterolateral setae; S8 much shorter than T8, narrowly divided medially into 2 pale-pigmented sclerites ( Fig. 42 ). Genital chamber with reduced internal sclerotization ( Fig. 46 , is): consisting of a single pair of submembranous, poorly delimited sclerites situated anterior to a well-sclerotized and curved annular sclerite with widened sides ( Fig. 47 ). Ventral receptacle ( Figs 45, 46 ) long, tube-like, with basal duct hyaline, middle part broad and darkened, and apex vermicularly twisted but relatively short; remnant of accessory gland small, granulose ( Fig. 46 ), on slender duct having its widest part somewhat ringed. Spermathecae (1+1) on extremely long ducts, pyriform, one distinctly larger than the other ( Figs 43, 44 ), each with slightly de- pressed apex, transversely striated surface in distal half, small tuberculiform spinulae on basal half, and small brownish cervix. T10 small but elongately shield-shaped ( Fig. 41 ), very pale, with single medial pair of relatively short setae and reduced micropubescence. S10 broader and longer than T10, elongately rounded pentagonal ( Fig. 42 ), with very dense fine micropubescence and fine marginal setae. Cercus ( Figs 40, 41 ) long and slender (in contrast to that of A. flavosterna ), pale-pigmented, with apical and dorsopreapical setae longest but both shorter than cercus. Discussion. Anthomyza caesarea sp. nov. so closely resembles the species of the genus Epischnomyia Roháček, 2006 in body and wing colouration that it had originally been considered a member of this East Asian genus. However, the examination of the male and female terminalia revealed this large Anthomyza species with distinctly longitudinally banded wings ( Fig. 24 ) is related to A. flavosterna . Four additional species allied to the latter species have been discovered in Taiwan, which are now placed in the separate A. flavosterna group (see above). However, A. caesarea sp. nov. is the most aberrant of these relatives differing from all of them, not only by the patterned wings but also by the most derived characters of the male terminalia (reduced cerci and anal fissure, narrow and acute gonostylus, large and broad filum of distiphallus, no sclerotized armature of aedeagal part of folding apparatus) and female postabdomen (very small S6, large and strongly modified T7+S7 with S7 reduced to a membranous medial strip, elongated and pale-pigmented 8th + 10th abdominal segments). Based on some shared apomorphic characters, this new species seems to be the nearest ally of A. elongata sp. nov. (for their synapomorphies, see discussion under the latter species).

Etymology. This new species is named to reflect its large, unusally bicoloured body and longitudinally brown-patterned wings (caesareus = imperial, Latin adjective).

Biology. Unknown. The type specimens (1 male 2 females) were swept from vegetation in June in a montane location (about 2400–2500 m).

Distribution. Taiwan: Taichung City area.

Figures

Figs 22–27. Anthomyza species from Taiwan.22–25 – A. caesarea sp. nov., male and female: 22 – male holotype before dissection, laterally (body length ca. 3.3 mm); 23 – female paratype before dissection, laterally (body length ca. 3.4 mm); 24 – wing, female paratype (length ca. 3.9 mm); 25 – female paratype before dissection, laterally (body length ca. 3.5 mm); 26–27 – A. elongata sp. nov., female: 26 – wing, female paratype (length ca. 3.7 mm); 27 – female holotype, laterally (body length ca. 3.4 mm). Photos by J. Roháček.

Figs 28–32. Anthomyza caesarea sp. nov., male holotype, female paratype. 28 – end of male abdomen in situ, laterally; 29 – female f1, posteriorly; 30 – male trochanter, f2 and t2, posteriorly; 31 – male trochanter, f3, t3 and hind basitarsus, anteriorly; 32 – male external genitalia, caudally. Scales = 0.2 mm (Figs 28, 32), 0.3 mm (others). For abbreviations see pp. 270–271.

Figs 33–39. Anthomyza caesarea sp. nov., male holotype. 33 – hypandrium, ventrally; 34 – transandrium, caudally; 35 – hypandrium, laterally; 36 – gonostylus, lateroventrally (widest extension); 37 – base of phallapodeme, dorsally; 38 – aedeagal complex, laterally; 39 – apex of filum of distiphallus, ventrally. All scales = 0.1 mm. For abbreviations see p. pp. 270–271.

Figs 40–47. Anthomyza caesarea sp. nov., female paratype. 40 – postabdomen, laterally; 41 – the same, dorsally; 42 – the same, ventrally; 43–44 – spermathecae; 45 – ventral receptacle, subventrally; 46 – genital chamber with 8th abdominal segment, laterally; 47 – annular sclerite, ventrally. Scales = 0.2 mm (Figs 40–42), 0.03 mm (Figs 43, 44) and 0.1 mm (others). For abbreviations see pp. 270–271.